Add max-line-width 70ch for redability.

assets/sass/_variables.scss

@@ -123,6 +123,9 @@ $breakpoints: (
 // The max content width.
 $max-content-width: 960px;
 
+// The max line width for redability.
+$max-line-width: 70ch;
+
 // The default left/right gutter/padding.
 $zen-gutters: 20px;
 

assets/sass/reset/sections/_sections.scss

@@ -67,3 +67,14 @@ h6,
   @include margin-bottom(1, xs);
   line-height: 1.3;
 }
+
+// Set max text line width for redability.
+
+h2,
+h3,
+h4,
+h5,
+h6,
+p {
+  max-width: $max-line-width;
+}